This invention relates to improved apparatus for marking conductive parts and, in particular, to apparatus for selectively recording alpha-numeric characters upon conductive parts using an electrochemical marking technique.
In the electrochemical marking process, a grounded conductive part is marked by firing an electrode through a stencil in the presence of an electrolyte so that the electrical current reaching the receiving surface of the part is shaped by the stencil design. As a result, a latent electrical image of the design is recorded upon the receiving surface of the part. Under the influence of the electrolyte, an etch is formed within the imaged area and, at the same time, an oxide of the base metal is deposited in the etched regions to create a relatively darker and thus clearly visible mark. The electrochemical marking process does not deform or otherwise harm the receiving part. Similarly, because it is clean and easy to use and also provides a permanent mark, the process has found widespread use in industry.
Heretofore, in the practice of the electrochemical marking process, it has been necessary to cut a new stencil every time recorded data placed upon the part changed. In the situation where different identification or serial numbers were to be placed on parts, a large number of stencils were required. Handling of the stencils was an extremely difficult and time-consuming procedure. Similarly, the process was susceptible to human error which resulted in parts being mismarked. Correcting this type of error oftentimes resulted in the scraping of the part or having to remark it. In any case, correcting marking errors is a generally expensive proposition.